Up to date Anesthesia Monitoring

Category: Education

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Principle of anesthesia monitoring Dr.Thepakorn Sathitkarnmanee รศ.นพ.เทพกร สาธิตการมณี


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Up to date Anesthesia Monitoring:

Up to date Anesthesia Monitoring รศ.นพ.เทพกร สาธิตการมณี ภาควิชาวิสัญญีวิทยา คณะแพทยศาสตร์ มหาวิทยาลัยขอนแก่น

Patient Monitoring:

... interpret available clinical data to help recognize present or future mishaps or unfavorable system conditions Involves … Things you measure (physiological measurement, such as BP or HR) Things you observe (e.g. observation of pupils) Planning to avoid trouble (e.g. planning induction of anesthesia or planning extubation) Inferring diagnoses (e.g. unilateral air entry may mean endobronchial intubation) Planning to get out of trouble (e.g. differential diagnosis and response algorithm formulation) Patient Monitoring

Monitoring in the Past:

Visual monitoring of respiration and overall clinical appearance Finger on pulse Blood pressure (sometimes) Monitoring in the Past


STANDARD I Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthetics, regional anesthetics and monitored anesthesia care. STANDARD II During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature shall be continually evaluated. STANDARDS FOR BASIC ANESTHETIC MONITORING

Detecting Mishaps Using Monitors:

Detecting Mishaps Using Monitors 1. Disconnection 2. Hypoventilation 3. Esophageal intubation 4. Bronchial intubation 5. Circuit hypoxia 6. Halocarbon overdose 7. Hypovolemia 8. Pneumothorax 9. Air Embolism 10. Hyperthermia 11. Aspiration 12. Acid-base imbalance 13. Cardiac dysrhythmias 14. IV drug overdose Source: Barash Handbook These mishaps …

Detecting Mishaps with Monitors:

Pulse oximeter 1,2,3,4,5,8,9,11,14 Mass spectrometer 1,2,3,6,9,10,12 Capnograph 1,2,3,9,10,12 Automatic BP 6,7,9,14 Stethoscope 1,3,4,13 Spirometer 1,2 Oxygen analyzer 5 EKG 13 Temperature 10 Source: Barash Handbook Detecting Mishaps with Monitors … are detected using these monitors

Basic Monitoring :

Cardiac: Blood Pressure, Heart Rate, ECG ECG: Rate, ST Segment (ischemia), Rhythm Respiratory: Airway Pressure, Capnogram , Pulse Oximeter, Spirometry , Visual Cues Temperature [pharyngeal, axillary , esophageal, etc.] Urine output (if Foley catheter has been placed) Nerve stimulator [face, forearm] (if relaxants used) ETT cuff pressure (keep < 20 cm H 2 O) Auscultation (esophageal or precordial stethoscope) Visual surveillance of the anesthesia workspace and some exposed portion of the patient Basic Monitoring

Visual Surveillance:

Anesthesia machine / workspace checkout Patient monitor numbers and waveforms Bleeding/coagulation (e.g., are the surgeons using a lot of suction or sponges? ) Diaphoresis / movements / grimaces Line quality (is my IV reliable?) Positioning safety review Respiratory pattern (e.g. tracheal tug, accessory muscle use etc.) Visual Surveillance

Low Tech Patient Monitoring:

Manual blood pressure cuff Finger on the pulse and forehead Precordial stethoscope (heart and breath sounds) Eye on the rebreathing bag (spontaneously breathing patient) Watch respiratory pattern Watch for undesired movements Look at the patient’s face color OK? diaphoresis present? pupils Low Tech Patient Monitoring

High Tech Patient Monitoring:

High Tech Patient Monitoring Examples of Multiparameter Patient Monitors

High Tech Patient Monitoring:

High Tech Patient Monitoring Some Specialized Patient Monitors Depth of Anesthesia Monitor Evoked Potential Monitor Transesophageal Echocardiography

Special Monitoring:

Pulmonary artery lines (Swan Ganz ) Transesophageal echocardiography Intracranial pressure (ICP) monitoring Electrophysiological CNS monitoring Renal function monitoring (indices) Coagulation monitoring (e.g. ACT) Acid-base monitoring (ABGs) Monitoring depth of anesthesia Special Monitoring


Purpose: Alarms serve to alert equipment operators that some monitored variable or combination of variables is outside some region Motivation: recognition of limited attentiveness capability in humans, even under good operating conditions Alarms

8 Axes of Clinical Anesthesia Monitoring (A Conceptual Model):

Axis I - Airway /Respiratory Axis II - Circulatory / Volume Axis III - Depth of Anesthesia Axis IV - Neurological Axis V - Muscle Relaxation Axis VI - Temperature Axis VII - Electrolytes / Metabolic Axis VIII - Coagulation 8 Axes of Clinical Anesthesia Monitoring (A Conceptual Model)

Airway / Respiratory Axis:

Correct ETT placement ETT cuff pressure Airway pressure Oxygenation Ventilation Spirometry Pulmonary biomechanics Airway gas monitoring Clinical: wheezing, crackles, equal air entry, color, respiratory pattern (rate, rhythm, depth, etc.) Airway / Respiratory Axis

Circulatory Axis:

Cardiac output Input pressures (CVP, LAP) Output pressures (BP, PAP) Pacemaker: rate, conduction Cardiac contractility Vascular resistances (SVR, PVR) Intracardiac shunts Circulatory Axis

Cardiac Monitoring Methods:

Symptoms and signs: angina, diaphoresis, mental state Finger on the pulse: rate, rhythm, pulse “volume” Auscultation: rate, rhythm, murmurs, extra sounds Electrocardiogram : rate, rhythm, ischemia Pulse oximeter waveform: rate, rhythm Blood pressure: cuff, oscillotonometry , art. line Volume Status: low-tech, high-tech Cardiac Monitoring Methods

Depth of Anesthesia :

Depth of Anesthesia Clinical Signs eye signs respiratory signs cardiovascular signs CNS signs EEG monitoring Facial EMG monitoring (experimental) Esophageal contractility (obsolete)

CNS Monitoring:

Clinical: sensorium , reflexes, “wake up test” Electroencephalography: raw EEG, compressed spectral arrays (CSA), 95% spectral edge, etc. Evoked potentials (esp. somatosensory EPs) Monitoring for venous air emboli Intracranial pressure (ICP) monitoring Transcranial doppler studies (MCA flow velocity) (Research) Jugular bulb saturation (Research) Cerebral oximetry (Research) CNS Monitoring

Relaxation Axis:

Clinical Signs +/- Nerve Stimulator Mechanomyography Electromyography Piezoelectric methods Special methods (e.g. DBS) Relaxation Axis

Temperature Monitoring:

Rationale for use detect/prevent hypothermia monitor deliberate hypothermia adjunct to diagnosing MH monitoring CPB cooling/ rewarming Sites Esophageal Nasopharyngeal Axillary Rectal Bladder Temperature Monitoring

Electrolyte / Metabolic Axis:

Fluid balance Sugar Electrolytes Acid-base balance Nutritional status Electrolyte / Metabolic Axis

Coagulation Monitoring:

Clinical signs PT / PTT / INR ACT Platelet counts Factor assays TEG Coagulation Monitoring


Adult/Pediatric/Neonate Basic monitor ECG NIBP SpO 2 Advanced monitor CO 2 monitor Monitoring


Lead 3-lead 12-lead EASI method : 5 electrodes Conventional method : 10 electrodes Arrhythmia detection Ventricular arrhythmias, asystole , bradycardia Ischemia detection ST-segment analysis ECG


Conventional Pulse Oximetry provides inaccurate monitoring or signal dropout during: Patient Motion or Movement Low Perfusion (low signal amplitude) Intense Ambient Light (lighting or sunlight) Electro surgical Instrument Interference Advanced technology : Masimo SET Masimo SET uses Adaptive Filter, DST, FST and SST, in parallel processing  mode (all patented by Masimo ). Masimo SET's four unique algorithms, along  with conventional red over infrared algorithm allows for unprecedented fidelity,  sensitivity and specificity SpO 2

Masimo SET:

Masimo SET Barker SJ, Morgan S. Anesthesia and Analgesia 2004;98(55),S2:A6

Masimo SET:

Masimo SET

Pulse Pressure Variation  Hypovolemia:

Pulse Pressure Variation  Hypovolemia

Respiration–The BIG Picture:

Respiration–The BIG Picture

Capnography Depicts Respiration:

Capnography Depicts Respiration

Capnography & Pulse Oximetry:

Capnography & Pulse Oximetry CO 2 : Relects ventilation Detects apnea and hypoventilation immediately Should be used with pulse oximetry O 2 Saturation: Reflects oxygenation 30 to 60 second lag in detecting apnea or hypoventilation Should be used with capnography

Indications for Use - End-Tidal CO2 Monitoring :

Validation of proper endotracheal tube placement Detection and Monitoring of Respiratory depression Hypoventilation Obstructive sleep apnea Procedural sedation Adjustment of parameter settings in mechanically ventilated patients Indications for Use - End-Tidal CO 2 Monitoring

Normal Arterial & ETCO2 Values:

Normal Arterial & ETCO 2 Values

Physiological Factors Affecting ETCO2 Levels:

Physiological Factors Affecting ETCO 2 Levels

Value of the CO2 Waveform:

Value of the CO 2 Waveform The Capnogram : Provides validation of the ETCO 2 value Visual assessment of patient airway integrity Verification of proper ETT placement Assessment of ventilator/breathing circuit integrity

The Normal CO2 Waveform:

The Normal CO 2 Waveform A – B Baseline B – C Expiratory Upstroke C – D Expiratory Plateau D ETCO 2 value D – E Inspiration begins

Esophageal Tube:

Esophageal Tube A normal capnogram is the best evidence that the ETT is correctly positioned With an esophageal tube little or no CO 2 is present

Inadequate Seal Around ETT:

Inadequate Seal Around ETT Possible causes: Leaky or deflated endotracheal or tracheostomy cuff Artificial airway too small for the patient

Hypoventilation (increase in ETCO2):

Hypoventilation (increase in ETCO 2 ) Possible causes: Decrease in respiratory rate Decrease in tidal volume Increase in metabolic rate Rapid rise in body temperature (hypothermia)

Hyperventilation (decrease in ETCO2):

Hyperventilation (decrease in ETCO 2 ) Possible causes: Increase in respiratory rate Increase in tidal volume Decrease in metabolic rate Fall in body temperature (hyperthermia)


Rebreathing Possible causes: Faulty expiratory valve Inadequate inspiratory flow Insufficient expiratory flow Malfunction of CO 2 absorber system


Obstruction Possible causes: Partially kinked or occluded artificial airway Presence of foreign body in the airway Obstruction in expiratory limb of the breathing circuit Bronchospasm

Muscle Relaxants:

Muscle Relaxants “Curare Cleft”: Appears when muscle relaxants begin to subside Depth of cleft is inversely proportional to degree of drug activity

Faulty Ventilator Circuit Valve:

Faulty Ventilator Circuit Valve Baseline elevated Abnormal descending limb of capnogram Allows patient to rebreath exhaled gas

Sudden Loss of Waveform:

Sudden Loss of Waveform Apnea Airway Obstruction Dislodged airway (esophageal) Airway disconnection Ventilator malfunction Cardiac Arrest

ETCO2 & Cardiac Resuscitation:

Non-survivors Average ETCO 2 : 4-10 mmHg Survivors (to discharge) Average ETCO 2 : >30 mmHg ETCO 2 & Cardiac Resuscitation


CPR CPR Square box waveform ETCO 2 10-15 mm Hg (possibly higher) with adequate CPR Management: Change Rescuers if ETCO 2 falls below 10 mm Hg

ROSC (Return of Spontaneous Circulation):

ROSC (Return of Spontaneous Circulation) During CPR sudden increase of ETCO2 above 10-15 mm Hg Management: Check for pulse

CO2 monitor:

Mainstream Sidestream Microstream CO 2 monitor

Mainstream capnography:

Mainstream capnography

Mainstream capnography:

Mainstream capnography

Sidestream capnography:

Sidestream capnography

Sidestream capnography:

Sidestream capnography

Microstream capnography:

Microstream capnography

Microstream capnography:

Microstream capnography

Microstream capnography:

Microstream capnography

Microstream capnography:

Microstream capnography

Slide 62:

Thank You for Attention Q & A

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